Dynamic Sub-Block Allocation in 3D NAND Memory
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Solution Overview
Problem
The increasing number of word lines in three-dimensional NAND memory arrays leads to larger storage blocks, posing challenges in memory yield, bad block management, and block failure handling due to greater capacity loss with each failure, necessitating a solution for designing and handling larger physical and logical memory divisions.
Innovation Solution
Implementing a sub-block mode where each physical block is divided into two or more physical sister sub-blocks, allowing independent programming, erasure, and reading, with a die controller managing control lines to minimize impact on other sub-blocks within the same physical erase block, and blending sub-block and full-block modes to optimize storage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of word lines in three-dimensional NAND memory arrays is increased to expand storage capacity, then the storage block size increases, but the memory yield and reliability deteriorate due to greater capacity loss with each failure
Solution Approach 1:
The patent divides a physical erase block into multiple independent sub-blocks (first sub-block and second sub-block) separated by a fabrication joint. This segmentation allows independent programming and erasing of each sub-block, so that a failure in one sub-block does not necessitate erasing or retiring the entire physical erase block, thereby improving memory yield while maintaining large storage capacity.
2Quantity of substance
If the storage block size is increased to accommodate more word lines, then the storage capacity increases, but the block failure handling capability deteriorates due to larger capacity loss
Solution Approach 1:
By segmenting the physical erase block into independent sub-blocks, the system gains adaptability in failure handling. When a block failure occurs, only the affected sub-block needs to be retired, while other sub-blocks remain operational. This is managed through logical erase blocks that can be configured to span multiple physical erase blocks, providing flexibility in bad block management and extending the lifespan of memory devices.
3Quantity of substance
If the number of memory cell layers is expanded on either side of the fabrication joint, then the storage capacity increases, but the device complexity increases due to multi-die configuration management
Solution Approach 1:
The patent merges multiple physical erase blocks from different memory dies into logical erase blocks. This allows the system to manage complex multi-die configurations through a unified logical structure, where logical erase blocks can span across multiple physical erase blocks on different dies. The controller manages these logical structures, simplifying the complexity of multi-die configuration while enabling expanded storage capacity through additional memory cell layers.
Data Source
AI summary
A system, apparatus, and method for dynamic allocation of sub-blocks. First, a non-volatile memory array receives a set of write commands. The non-volatile memory array comprises multiple memory dies organized into metablocks. The metablocks are configured to span two or more memory dies. A stream manager determines a workload type for the set of write commands. A block allocation manager selects a target storage block to receive the set of write commands based on the workload type. The selected target storage block is configured to receive data blocks for the workload type and the block allocation manager directs the set of write commands to the target storage block.